An omnidirectional camera enables an image with a wide field-of-view range to be obtained with a single camera, and is therefore widely used in a variety of fields. Omnidirectional cameras are used in monitoring systems and the like, for example. An omnidirectional camera enables an omnidirectional image to be obtained using an omnidirectional lens optical system or omnidirectional mirror optical system.
When an omnidirectional image is acquired at high resolution there is a large amount of information, and therefore an image is often compressed before being sent to a channel or recorded on a recording medium.
Technologies that reduce the amount of omnidirectional image data are disclosed in Patent Literatures 1 and 2. Patent Literatures 1 and 2 disclose technologies that reduce the amount of omnidirectional image data by reducing the number of colors or increasing the compression rate of an image other than a circular image among rectangular images that include a circular image obtained by means of an omnidirectional camera.
Also, Patent Literature 3 discloses a technology that reduces the amount of image data by changing the compression rate according to an imaging location or imaged object.